Beta Blockers in Acute NSTEMI Management
Beta blockers should be administered orally within the first 24 hours to all patients with NSTEMI who do not have contraindications such as heart failure, low-output state, risk of cardiogenic shock, or other specific contraindications. 1
Indications and Timing
- Beta blockers are a Class I recommendation (standard of care) for all NSTEMI patients without contraindications, with treatment beginning within the first 24 hours of presentation 1
- Oral administration is the preferred initial route for most patients, though IV beta blockers may be considered in specific situations such as hypertension 1
- Early administration (within 24 hours) is associated with lower in-hospital mortality (adjusted odds ratio 0.66) and improved 6-month outcomes 2, 3
Contraindications and Caution Scenarios
Beta blockers should NOT be administered to patients with:
- Signs of heart failure 1
- Evidence of low-output state 1
- Increased risk for cardiogenic shock (age >70 years, systolic BP <120 mmHg, heart rate >110 or <60 bpm, increased time since symptom onset) 1, 4
- PR interval >0.24 seconds or second/third-degree heart block 1
- Active asthma or reactive airway disease 1
Benefits in NSTEMI
- Reduces myocardial oxygen demand by decreasing heart rate, blood pressure, and myocardial contractility 5
- Associated with lower in-hospital mortality in overall NSTEMI population (3.9% vs 6.9%, p<0.001) 2
- Particularly beneficial in patients with Killip class II/III heart failure (OR 0.39,95% CI 0.23-0.68) 3
- Continued indefinitely post-NSTEMI for secondary prevention 1
Cautions with Administration
- Very early use in the emergency department is associated with increased risk of shock compared to administration later within the first 24 hours 4
- Risk of shock increases with the number of risk factors present 4
- For patients with moderate to severe LV failure, beta blockers should be initiated with a gradual titration scheme 1
- Abrupt discontinuation should be avoided due to risk of exacerbating angina, myocardial infarction, or ventricular arrhythmias 6
Alternative Approaches
- When beta blockers are contraindicated, non-dihydropyridine calcium channel blockers (verapamil or diltiazem) should be given as initial therapy in the absence of severe LV dysfunction 1
- Extended-release forms of non-dihydropyridine calcium channel blockers may be considered instead of beta blockers in some patients (Class IIb recommendation) 1
Practical Administration
- Atenolol is commonly used in post-MI settings, with demonstrated mortality benefit in clinical trials 6
- For patients with borderline blood pressure (less than 120 mmHg systolic), especially if over 60 years of age, benefits may be less pronounced 6
- Monitor for common adverse effects including bradycardia (3%), dizziness (13%), and fatigue (26%) 6
- In patients with acute MI, cardiac failure not promptly controlled by furosemide is a contraindication to beta-blocker treatment 6
Beta blockers remain a cornerstone of NSTEMI management, with clear mortality benefits when appropriately administered to eligible patients. The key is careful patient selection, avoiding use in those with contraindications, particularly signs of heart failure or risk factors for cardiogenic shock.